The consumer-goods giant wanted to replace the problematic and bulky pails — the containers had both plastic and metal components, were difficult to convey and store on a pallet, took up lots of space and required about 144 pounds of excess packaging material to ensure they could be shipped successfully.

Clorox landed on flexible stand-up pouches as an ideal alternative, but transitioning to a new packaging format was a huge undertaking that wasn't taken lightly, said Cecilia Melby, associate research fellow at Clorox and leader of the project.

Melby outlined the packaging conversion in a talk at the Society of the Plastics Industry Inc.'s Flexible Film and Bag conference in Nashville.

The Oakland, Calif.-based company had to balance both consumer and retail considerations. The 42-pound packages of litter are sold at club stores, like Costco and Sam's Club, that have varying display requirements, so they needed to look good from all sides. The packages needed to remain stable during shipping — stores will reject shipments that shift during transit — and arrive without leaks or other failures. Clorox also wanted a more sustainable package.

To entice customers to transition to the pouch, the new package would have to maintain some of the features of the pail. Namely, the pouch would have to be easy to carry and use — whether pouring or scooping litter — and be resealable or reclosable.

The two companies developed the package "from day one until three months before launch," Melby laughed.

The developers tested different materials, sizes and features. They then put at least seven different structures through numerous trials including shipping and stack testing, consumer handling tests, drop tests and fill trials.

The final package is a multilayer bag — a PET outer layer laminated to a nylon middle layer and a polyethylene inner layer — reverse-printed in an eight-color gravure process. The specific gauge and other structural details are proprietary.

The final package offers an 80 percent reduction in materials.

The pouches stay stable when shipped vertically and can be palletized and stacked 4-by-4. The developers found they could tie sheets and a stretch hood — which Melby jokingly compared to a swim cap — to secure packages on the pallet. Shipping the pouches requires 14 pounds of dunnage, compared with the more than 100 pounds needed to ship pails.

The pouches are more stable during shipping and less likely to become damaged during distribution.

"You could open up a truck with pails and it would look like a bunch of cracked eggs," Melby said. If something caused a significant shift during transportation, there could be catastrophic failures. "We don't see that at all with the bags."

The pouch is less puncture-resistant — no matter how thick you make a pouch or what materials you use, the reality is that "if you stick a fork truck in it, the bag's going to break," she said.

But in normal scenarios, the company feels it now has a package that works for the company and for consumers.

Initial development work was done at Mondi's plant in Germany. Once the team settled on a design, Mondi began operating a dedicated line in the U.S. to produce the package.

Developing the package was not without hurdles.

The biggest challenge in converting from a rigid package to a flexible one was in understanding how the flexible package behaved, not only in the supply chain but in getting the package filled, closed, folded and palletized, said Mark Gum, a process engineer at Mondi.

"It's completely different," he said.

Gum was not able to attend the conference but joined Melby for the presentation remotely.

Litter packages are filled by weight, but because litter is a natural material made with clay there are differences in density from load to load. Packages can vary 1-2 inches per filling line, Gum said.

Developers had to determine the correct bag dimensions to accommodate those variations. Mondi also had to engineer its filling machines to constantly compensate for changes in density and incorporate a load cell weight filling to guarantee accuracy.

Mondi had to engineer its filling lines to drop 42 pounds of litter into a bag at high speeds.

"It was all we could do without changing gravity," Gum joked. "I just didn't have enough time to work on that."

Sealing the package was critical.

The bag has a gusset top that allows the headspace to be folded down and taped to make a square, stackable shape.

A horseshoe label is used to tape the flaps down. Shoppers tend to grab the pouch from the top and throw it in their cart, so the label had to be strong and functional, Gum said.

"You don't want to drop 42 pounds of litter on someone's foot or toes," he said.

Mondi developed a proprietary label design that doubles as a multi-ply handle and found an adhesive strong enough to allow the label to support the full weight of the package.

The bags are held by the top throughout filling and sealing to ensure sealing accuracy and seal windows in spite of density variations.

There was also development work involved in finding a closure for the bag. Clorox went with a slider closure provided by Pactiv Corp. Once the slider was selected, the team did additional testing to determine factors like opening force, tamper evidence, clip retention and a slider plow that prevented product from getting in the way of the closure.

Clorox launched the package in 2010. Despite an initial dip in sales, sales volume has increased by more than 50 percent since the launch.

First reactions were not all positive, Melby said. "Our consumer complaints database went crazy. People wanted their pail back."

Consumers said they bought pails every month and then used the empty packages for other things. Clorox appeased those customers by offering a 40 pound pail alongside the 42 pound pouch. Pricing was also more competitive.

The pouch also has sustainability benefits, despite concerns about recycling.

The multimaterial pouch is not easily recyclable, but the polypropylene pail really wasn't either, Melby said. Many municipal recycling facilities considered the pails too large to process.

Both packages were going to a landfill, but with the pouches, 80 percent less material is being thrown away, she said.

Most of the metrics on Wal-Mart Stores Inc.'s supplier sustainability scorecard are weight-based, so the pouch was a huge improvement, she added.